The present invention relates to a method for producing permanent magnets and sintered compact. More particularly, the present invention relates to a method for compacting a permanent-magnet powder under a magnetic field while enhancing the anisotropic property and hence enhancing the magnetic properties of the permanent magnets so made. The particles of the powder as compacted are oriented in the easy direction of magnetization. The so-oriented particles are then subjected to compacting and the particles are fixed by the compacting force. The green compact is then sintered to obtain the sintered magnet. Alternatively, resin is impregnated into the so-oriented powder so as to obtain the resin-bonded magnet. The permanent-magnet (hereinafter referred to as the "magnet") powder and resin may be compacted together to obtain the resin bonded magnet.
In addition, the present invention relates to a method for producing a sintered compact by means of die-pressing a fine powder of an ordinary material, i.e., a material other than a magnet material, under no magnetic field and then sintering the green compact. More particularly, the conventional diepressing method is improved such that the fine powder is compacted. In the powder-metallurgy technique, not only the density of a sintered compact increases but also the grain size of a sintered compact can be refined by lessening the particle diameter of the powder. As a result, the such sintered materials as Al and Ti are considerably strengthened, and the magnetic properties of soft magnetic ferrous materials are enhanced. However, the flowability of fine powder is very poor. When the powder having poor flowability is filled in a die under gravity, the bridging phenomenon is very liable to occur in the die, and the filling density greatly varies for each filling. The weight of each green compacts (hereinafter referred to as "unit weight") varies greatly and the average filling density of the powder is lower.
The present invention is also related to production apparatus of a green compact, which is subjected to sintering, or to the production of magnet.